sb-220.something added not sure why

Discussion in 'Amateur Radio Amplifiers' started by KD5JRV, Mar 14, 2011.

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  1. KM1H

    KM1H Ham Member QRZ Page

    The 1N5408's are a good idea but the PC board holes have to be enlarged a bit. Also be easy on the diode lead bending and leave a 1/2" or more exposed above the board. The leads are the diodes heat sink plus sharp bends right at the case can fracture them.

  2. K9STH

    K9STH Ham Member QRZ Page

    If you don't have a Dremel (or similar small drill), you can use an Xacto knife with a #11 blade to enlarge the holes in the circuit board for the 1N5408 diode leads. Just insert the blade and turn the handle a few times. Then do the same thing on the "other" side of the circuit board. If you just do one side, the hole is going to be "cone" shaped.

    Glen, K9STH
  3. KD5JRV

    KD5JRV Ham Member QRZ Page

    thanks for the help. i have the capacitors and bleeders coming from mouser, the soft start and soft key coming from harbach. i have blacked out the tube section in the amp to cut down on reflection.and a buddy of mine has a metering board for it already. i will post a pic of where i am at later

    thanks again
  4. KM1H

    KM1H Ham Member QRZ Page

    You could generate a lot of arguments about using black on the inside of the RF cage:confused:

    All I know it was very seldom used in any commercial and no military amp that Im aware of.
  5. W0BTU

    W0BTU Ham Member QRZ Page

    I think the idea must be to prevent heat from being reflected back into the cage. Black is both a better absorber and a better radiator of heat.

    Not to start an argument, but how can that be really worthwhile? Where's the heat going to go? It's not going to just disappear. You would have to blacken both sides and remove the heat externally. I don't think you'll gain much, if anything.
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